First, the brake pedal should be depressed multiple times with the engine off, and then with the engine on, and if the pedal goes down slightly, the operation is fine. The airtightness of the booster can be checked by starting the engine and turning it off, then depressing the brake pedal and if it depresses less, the booster is airtight. The process of removing a new power brake booster unit involves detaching the vacuum hose, removing the nuts linking the master cylinder, the power brake pushrod, the nuts attaching the booster to the firewall, and carefully pulling the unit out. Also, the new unit should be installed by tightening the nuts, attaching the brake pedal and the return spring, checking the pushrod clearance, installing the
Brake Master Cylinder, reattaching the vacuum hose, adjusting the brake pedal height and free play, and testing the brakes.